Today's water pumps are significantly more durable than those from "back when". They are designed to "dry run" without damage. That said, continued operation can cause damage, but I'd say that if it's working, consider it operational and keep using it. You can buy replacement pumps anywhere from $50 to "north of $300". So, what you replace it with will determine how much it costs when (if) it fails. If you want to replace with a similar pump, it'll be around $75 to $100 for the pump. Installation costs can be as much or even more than the cost of the pump, so if you're handy, save yourself some money.
All said and done, your current pump may fail this weekend, or: It could run without a hic-cup for another 10 years.......
2015 F250 6.7l 4x4
2014 Cougar X Lite 27RKS